• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.128-130
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• 2003

In recent years, both utilities and users have expressed their deep concerns about the quality of electric power. Expressed, voltage sag which is one of power quality disturbance is very serious power quality problem on the power system. Voltage sag is a decrease to between 0.1 and 0.9 pu in rms voltage magnitude on the power system for durations from 0.5 cycles to 1 minute. These voltage sags are usually caused by fault condition, overload, and starting of large motors. In this paper, different types of voltage sags are simulated by using EMTP. This paper describes the distinctive characteristic for various sag origins, proposes the effective technique for voltage sag detection using EMTP.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.77-88
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• 1993

This paper shows the methods about an improvement of the sound quality, which is improvement for automobil market recently. Especially, the rumble noise in the passenger compartment makes driver uncomfortable. For an improvement of the rumble noise, in this paper, the increase of the number of balance weight of the crank shaft(from 4 to 8), the vibration constrainer of cylinder block and the flexible flywheel were applied to power plant. Among those kinds of applications, the application of the flexible flywheel to power plant makes not only the vibration of the engine mount boss reduce most effectly but also the interior noise. It also improves the sound quality and the rumble noise disappears in the passenger compartment.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.994-995
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• 2006

This paper presents a grid-connected photovoltaic (PV) system with direct coupled power quality control (PQC) algorithm, which uses an inner current control loop (PRT : polarized ramp time) and outer feedback control loop to improve grid power quality and maximum power point tracking (MPPT) of PV arrays. To reduce the complexity, cost and number of power conversions, which results in higher efficiency, single stage CCVSI (Current Controlled Voltage Source Inverter) is used. The proposed system operation has been divided into two modes (sunny and night). In night mode, the proposed system operates to compensate the reactive power demanded by nonlinear or variation in loads. in sunny mode, the proposed system performs PQC to reduce harmonic current and improve power factor as well as MPPT to supply active power from the PV arrays simultaneously. it is shown that the proposed system improves the system utilization factor to 100% which is generally low for PV system (20%). To verify the proposed system, a comprehensive evaluation with theoretical analysis and simulation results are presented.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.253-257
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• 2016

This paper analyzes voltage control method in order to supply high-quality power for stand-alone microgrid. Stand-alone microgrid is composed of battery bank, stand-alone PCS and controllable loads. The main role of stand-alone PCS is to supply high-quality power to loads as main source by using stable voltage method regardless of load conditions. In particularly, output voltage of stand-alone PCS gets severely unbalanced voltage under unbalanced loads. Fundamental positive and negative sequences are transformed by two coordinates transformation which are rotated in each opposite direction, respectively. Each fundamental d-q voltage is regulated by each fundamental PI control. In addition, low-order harmonics are compensated through resonant controllers. Performance of stand-alone microgrid is tested for feasibility, and it is verified that output voltage of THD is improved to 1% from 2.2% under 50 kW balanced load, and is improved to 1.1% from 2.6% under 50 kW unbalanced load.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.707-712
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• 2006

Knowing the ground thermal conductivity is very importnat in designing ground heat exchangers. Knowledge of the ground soil and rock composition information dose not guarantee the prediction of accurate thermal information. In Situ testing of ground heat exchangers is becoming popular. However, in situ testing are performed at construction sites in real life. Adequate data collection and analysis are not easy mainly due to poor power quality. Power fluctuation also causes the fluctuation of received data. The power quality must be maintained during the entire in situ testing processes. To accurately analyse the test data, the understanding of the response of the power fluctuation is essential. Testing under the power quality varied by tester is very difficult. Analyzing power variation by numerical simulation is a realistic option. By varying power in a sinosuidal manner, its effects on predicting thermal conductivity from thermal response plots made from the test data are examined.

• Journal of Korean Society for Quality Management
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• v.46 no.2
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• pp.351-374
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• 2018

Purpose: The collective civil complaint problem is considered as important obstructive factor of the nuclear power plant construction project's success and quality. Therefore, this study demonstrate the factors which can affect the settling collective civil complaints, and also suggest the improvement of the resolution. Methods: This study collected the data of Kori Nuclear Power Division staff, local residents and Hanul Nuclear Power Division staff, local residents, and use them for analysis. Results: The results are twofold in the study: First, the 'Situation Recognition' and 'Mutual Cooperation' which are independent variables for solving collective civil complaints have proved to give positive influence on both the nuclear staff and the local residents about the complaint resolution outcome of the dependent variable. Second, the moderation variable 'Expected Benefit' on the influential relationship between the collective civil complaint resolution factor and the civil complaints resolution outcome proved to have a moderating effect only on the nuclear staff. On the other hand, moderation variables 'Time of SOC Business Implementation' and 'Time of Compensation' proved to have a moderating effect only for the local residents. Conclusion: According to the results, the staff have a positive opinion on the benefits of the nuclear power plant construction, while residents feel strongly that they do not get any benefit from the construction despite of tremendous investment and expected benefit in local area. As this results, policy implementation which is superable different understanding is required.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.130-137
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• 2003

Because of falling-off in power quality by harmonics, obstacles like lowering of capability, noise, vibration of power facilities and so on are occurred. Also generation of harmonics is inevitable and the point at harmonics is seriously gathering strength because energy saving installation using semiconductor circuit as countermeasures to enhance energy efficiency will be broadly spread and the use of energy conversion equipment like motor speed control contrivance, energy keeping installation and so on will increase, in the future. In order to eliminate harmonics obstacle, precision measurement and analysis on voltage, current, power factor, the each ingredient of harmonic order, the percentage of total harmonic distortion, and so forth are needed. In this paper, we developed low-cost measurement system to measure and analyze power quality connected with harmonics and verified it's performance by measuring and analyzing power quality in the three-phase and four-wire system.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.468-479
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• 2016

In order to supply power to online monitoring systems that are attached to high voltage catenary or overhead wires, a wireless power transfer system is required that is able to transmit power over the insulation gap. Such wireless power transfer systems have transmitter and receiver coils that have diameters of over 10cm. This paper focused on an investigation of the sources of loss in the coils when the coils are fabricated using printed circuit board technology. Using finite element simulation results, it has been shown that the dielectric loss in the substrate was the dominant source of the total loss. It has been demonstrated that the selection of a proper dielectric material was the most critical factor in reducing the loss. For further reduction of the loss, the distributed tuning capacitor method and the slotting of the inter-turn spaces have been proposed. For the evaluation of the proposed methods, four coils have been fabricated and their equivalent series resistances and quality factors were measured. Measured quality factors were greater than 300, which means that these devices will be helpful in achieving high coil-to-coil efficiency.

• Research in Community and Public Health Nursing
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• v.27 no.3
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• pp.193-201
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• 2016

Purpose: The aim of the study is to determine factors influencing quality of caregiving by caregivers for the elderly with dementia. Methods: Data were collected from 87 caregivers for elders with dementia who had visited in Busan Metropolitan Center for Dementia and D-University hospital outpatient center from July 10 to September 30, 2015. A self-reported questionnaire was used to assess the severity of the elders' dementia and knowledge of dementia, burdens and quality of caregiving by the caregivers. The SPSS 21.0 version program was used for data analysis. Data were analyzed using descriptive statistics, Pearson's correlation, t-test, ANOVA and multiple regression. Results: Significant predictors of quality of caregiving by caregivers included caregivers' burdens (explanation power 25%), knowledge of dementia (explanation power 4%) and levels of education (explanation power 3%). These factors explained 32.3% of the variances in quality of caregiving. Conclusion: Burdens on caregivers were a major factor that decreased quality of caregiving, and knowledge of dementia was a factor that increased it. These findings show that educational programs and intervention for reducing burdens and improving knowledge of dementia are necessary to improve quality of caregiving by caregivers.

• Journal of the Korean Home Economics Association
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• v.48 no.3
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• pp.15-30
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• 2010

The objective of this study is to identify the relationship quality and relationship benefit, which has greater explanatory power in predicting fashion consumers' future loyalty. This study is particularly interested in the different explanatory power of each relationship quality with various relationship partners of fashion consumers. The participants were 507 female consumers over 20 years old and they responed questionnaire. The result showed that relationship quality types and relationship benefits having greater explanatory power in predicting consumers' loyal relationship intention varied with multi-loyal relations. Consumers' intention to be loyal to an apparel brand and apparel company was more explained by self attachment than by any other relationship quality types, whereas the intention to be loyal to specific department store was predicted by low involved relationship quality types such as habitual alternative and compensational bind. Trusted intimacy was the only relationship quality type that was significant in predicting consumers' intention to be loyal to salesperson in the future. Among relationship benefits, the influence of convenience benefit was significant in predicting consumers' future loyalty in most relations.